Defective Epstein-Barr virus specific suppressor T cell function in progressive systemic sclerosis

Several immunoregulatory defects of Epstein-Barr virus (EBV) induced B cell activation have been described in patients with rheumatoid arthritis (RA), suggesting that EBV may have a role in the pathogenesis of RA. We assessed EBV specific T cell regulation in 20 patients with progressive systemic sclerosis (PSS) and immune to EBV and in 10 control subjects also immune to EBV by comparing the secretion of IgM into supernatants of 16 day cultures of B cells alone and cocultures of B and autologous T cells. In control subjects autologous T cells mediated a significant decrease in the secretion of IgM by B cells at 12 and 16 days of culture. Analysis of individual responses showed the existence of two subgroups of patients with PSS: group I (10 patients) had a suppressor T cell function similar to that of controls; group II (10 patients) had a defective T cell function. Differences in the duration or severity of the disease, the slow acting therapeutic agents, and anti-inflammatory drugs could not account for these subdivisions. These results suggest that several immunoregulatory defects of EBV induced B cell activation exist in different connective tissue diseases.